The present invention relates to arthropod esterase nucleic acid molecules, proteins encoded by such nucleic acid molecules, antibodies raised against such proteins, and inhibitors of such proteins. The present invention also includes therapeutic compositions comprising such nucleic acid molecules, proteins, antibodies, and/or other inhibitors, as well as their use to protect an animal from hematophagous arthropod infestation.
Hematophagous arthropod infestation of animals is a health and economic concern because hematophagous arthropods are known to cause and/or transmit a variety of diseases. Hematophagous arthropods directly cause a variety of diseases, including allergies, and also carry a variety of infectious agents including, but not limited to, endoparasites (e.g., nematodes, cestodes, trematodes and protozoa), bacteria and viruses.
In particular, the bites of hematophagous arthropods are a problem for animals maintained as pets because the infestation becomes a source of annoyance not only for the pet but also for the pet owner who may find his or her home generally contaminated with insects. As such, hematophagous arthropods are a problem not only when they are on an animal but also when they are in the general environment of the animal.
Bites from hematophagous arthropods are a particular problem because they not only can lead to disease transmission but also can cause a hypersensitive response in animals which is manifested as disease. For example, bites from fleas can cause an allergic disease called flea allergic (or allergy) dermatitis (FAD). A hypersensitive response in animals typically results in localized tissue inflammation and damage, causing substantial discomfort to the animal.
The medical importance of arthropod infestation has prompted the development of reagents capable of controlling arthropod infestation. Commonly encountered methods to control arthropod infestation are generally focused on use of insecticides. While some of these products are efficacious, most, at best, offer protection of a very limited duration. Furthermore, many of the methods are often not successful in reducing arthropod populations. In particular, insecticides have been used to prevent hematophagous arthropod infestation of animals by adding such insecticides to shampoos, powders, collars, sprays, foggers and liquid bath treatments (i.e., dips). Reduction of hematophagous arthropod infestation on the pet has been unsuccessful for one or more of the following reasons: (1) failure of owner compliance (frequent administration is required); (2) behavioral or physiological intolerance of the pet to the pesticide product or means of administration; and (3) the emergence of hematophagous arthropod populations resistant to the prescribed dose of pesticide. However, hematophagous arthropod populations have been found to become resistant to insecticides.
Prior investigators have described insect carboxylesterase (CE) protein biochemistry, for example, Chen et al., Insect Biochem. Molec. Biol., 24:347-355, 1994; Whyard et al., Biochemical Genetics, 32:924, 1994 and Argentine et al., Insect Biochem. Molec Biol, 25:621-630, 1995. Other investigators have disclosed certain insect CE amino acid sequences, for example, Mouches et al., Proc Natl Acacd Sci USA, 87:2574-2578, 1990 and Cooke et al., Proc Natl Acad Sci USA, 86:1426-1430, 1989, and nucleic acid sequence (Vaughn et al., J. Biol. Chem., 270:17044-17049, 1995).
Prior investigators have described certain insect juvenile hormone esterase (JHE) nucleic acid and amino acid sequences: for example, sequence for Heliothis virescens is disclosed by Hanzlik et al., J. Biol. Chem., 264:12419-12425, 1989; Eldridge et al., App Environ Microbiol, 58:1583-1591, 1992; Bonning et al., Insect Biochem. Molec. Biol., 22:453-458, 1992; Bonning et al., Natural and Engineered Pest Management Agents, pp. 368-383, 1994 and Harshman et al., Insect Biochem. Molec. Biol, 24:671-676, 1994; sequence for Manduca sexta""s disclosed by Vankatesh et al., J Biol Chem, 265:21727-21732, 1990; sequence for Trichoplusia ni is disclosed by Venkataraman et al., Dev. Genet., 15:391-400, 1994 and Jones et al., Biochem. J., 302:827-835, 1994; and sequence for Lymantria dispar is disclosed by Valaitis, Insect Biochem. Molec. Biol., 22:639-648, 1992.
Identification of an esterase of the present invention is unexpected, however, because even the most similar nucleic acid sequence identified by previous investigators could not be used to identify an esterase of the present invention. In addition, identification of an esterase protein of the present invention is unexpected because a protein fraction from flea prepupal larvae that was obtained by monitoring for serine protease activity surprisingly also contained esterase proteins of the present invention.
In summary, there remains a need to develop a reagent and a method to protect animals or plants from hematophagous arthropod infestation.
The present invention relates to a novel product and process for protection of animals or plants from arthropod infestation. According to the present invention there are provided arthropod esterase proteins and mimetopes thereof; arthropod nucleic acid molecules, including those that encode such proteins; antibodies raised against such esterase proteins (i.e., anti-arthropod esterase antibodies); and compounds that inhibit arthropod esterase activity (i.e, inhibitory compounds or inhibitors).
The present invention also includes methods to obtain such proteins, mimetopes, nucleic acid molecules, antibodies and inhibitory compounds. Also included in the present invention are therapeutic compositions comprising such proteins, mimetopes, nucleic acid molecules, antibodies, and/or inhibitory compounds, as well as use of such therapeutic compositions to protect animals from arthropod infestation.
Identification of an esterase of the present invention is unexpected, however, because the most similar nucleic acid sequence identified by previous investigators could not be used to identify an esterase of the present invention. In addition, identification of an esterase protein of the present invention is unexpected because a protein fraction from flea prepupal larvae that was obtained by monitoring for serine protease activity surprisingly also contained esterase proteins of the present invention.
One embodiment of the present invention is an isolated nucleic acid molecule that hybridizes under stringent hybridization conditions with a gene comprising a nucleic acid sequence including SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:51, SEQ ID NO:52, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:60, SEQ ID NO:61, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:70, SEQ ID NO:71, SEQ ID NO:72, SEQ ID NO:76 and/or a nucleic acid molecule encoding a protein comprising amino acid sequence SEQ ID NO:74.
The present invention also includes a nucleic acid molecule that hybridizes under stringent hybridization conditions with a nucleic acid molecule encoding a protein comprising at least one of the following amino acid sequences: SEQ ID NO:2, SEQ ID NO:5, SEQ ID NO:8, SEQ ID NO:11, SEQ ID NO:14, SEQ ID NO:19, SEQ ID NO:25, SEQ ID NO:31, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:39, SEQ ID NO:53, SEQ ID NO:54, SEQ ID NO:55, SEQ ID NO:58, SEQ ID NO:68, SEQ ID NO:73 and/or SEQ ID NO:74; and particularly a nucleic acid molecule that hybridizes with a nucleic acid sequence that is a complement of a nucleic acid sequence encoding any of the amino acid sequences. A preferred nucleic acid molecule of the present invention includes a nucleic acid molecule comprising a nucleic acid sequence including SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:51, SEQ ID NO:52, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:60, SEQ ID NO:61, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:70, SEQ ID NO:71, SEQ ID NO:72, SEQ ID NO:76 and/or a nucleic acid molecule encoding a protein comprising amino acid sequence SEQ ID NO:74, and allelic variants thereof.
The present invention also includes an isolated carboxylesterase nucleic acid molecule comprising a nucleic acid sequence encoding a protein comprising an amino acid sequence including SEQ ID NO:5, SEQ ID NO:19, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44 and/or SEQ ID NO:53, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43 and SEQ ID NO:44 represent N-terminal amino acid sequences of carboxylesterases isolated from prepupal flea larvae, the production of which are described in the Examples of the present application.
The present invention also relates to recombinant molecules, recombinant viruses and recombinant cells that include a nucleic acid molecule of the present invention. Also included are methods to produce such nucleic acid molecules, recombinant molecules, recombinant viruses and recombinant cells.
Another embodiment of the present invention includes an isolated esterase protein that is encoded by a nucleic acid molecule that hybridizes under stringent hybridization conditions to (a) a nucleic acid molecule that includes at least one of the following nucleic acid sequences: SEQ ID NO:3, SEQ ID NO:6, SEQ ID NO:9, SEQ ID NO:12, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:26, SEQ ID NO:29, SEQ ID NO:32, SEQ ID NO:35, SEQ ID NO:38, SEQ ID NO:52, SEQ ID NO:59, SEQ ID NO:61, SEQ ID NO:69, and SEQ ID NO:71; and/or (b) a nucleic acid molecule encoding a protein including at least one of the following amino acid sequences: SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44, SEQ ID NO:53, SEQ ID NO:54, SEQ ID NO:55 and SEQ ID NO:74. One embodiment is a carboxylesterase protein encoded by a nucleic acid molecule that hybridizes under stringent hybridization conditions to a nucleic acid molecule that encodes a protein comprising at least one of the following amino acid sequences: SEQ ID NO:5, SEQ ID NO:19, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44 and/or SEQ ID NO:53. Preferred proteins of the present invention are isolated flea proteins including at least one of the following amino acid sequences: SEQ ID NO:2, SEQ ID NO:5, SEQ ID NO:8, SEQ ID NO:11, SEQ ID NO:14, SEQ ID NO:19, SEQ ID NO:25, SEQ ID NO:31, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44, SEQ ID NO:53, SEQ ID NO:54, SEQ ID NO:55, SEQ ID NO:58, SEQ ID NO:68, SEQ ID NO:73 and SEQ ID NO:74; also included are proteins encoded by allelic variants of nucleic acid molecules encoding proteins comprising any of the above-listed amino acid sequences.
The present invention also relates to mimetopes of arthropod esterase proteins as well as to isolated antibodies that selectively bind to arthropod esterase proteins or mimetopes thereof. Also included are methods, including recombinant methods, to produce proteins, mimetopes and antibodies of the present invention.
The present invention also includes a formulation of flea carboxylesterase proteins, in which the proteins, when submitted to 14% Tris-glycine SDS-PAGE, comprise a fractionation profile as depicted in FIG. 3, in which the proteins have carboxylesterase activity.
Also included in the present invention is a formulation of flea carboxylesterase proteins, in which the proteins, when submitted to IEF-PAGE, comprise a fractionation profile as depicted in FIG. 4, lane 3, lane 4, lane 5, lane 6 and/or lane 7, wherein the proteins have carboxylesterase activity.
Another embodiment of the present invention is an isolated flea protein or a formulation of flea proteins that hydrolyzes xcex1-napthyl acetate to produce xcex1-napthol, when the protein is incubated in the presence of xcex1-napthyl acetate contained in 20 mM Tris at pH 8.0 for about 15 minutes at about 37xc2x0 C.
Yet another embodiment of the present invention is an isolated flea protein or a formulation of flea proteins that hydrolyzes the methyl ester group of juvenile hormone to produce a juvenile hormone acid.
Another embodiment of the present invention is a method to identify a compound capable of inhibiting flea carboxylesterase activity, the method comprising: (a) contacting an isolated flea carboxylesterase with a putative inhibitory compound under conditions in which, in the absence of the compound, the protein has carboxylesterase activity; and (b) determining if the putative inhibitory compound inhibits the activity. Also included in the present invention is a test kit to identify a compound capable of inhibiting flea carboxylesterase activity, the test kit comprising an isolated flea carboxylesterase protein having esterase activity and a means for determining the extent of inhibition of the activity in the presence of a putative inhibitory compound.
Yet another embodiment of the present invention is a therapeutic composition that is capable of reducing hematophagous ectoparasite infestation. Such a therapeutic composition includes at least one of the following protective compounds: an isolated hematophagous ectoparasite carboxylesterase protein or a mimetope thereof, an isolated carboxylesterase nucleic acid molecule that hybridizes under stringent hybridization conditions with a Ctenocephalides felis carboxylesterase gene, an isolated antibody that selectively binds to a hematophagous ectoparasite carboxylesterase protein, and an inhibitor of carboxylesterase activity identified by its ability to inhibit the activity of a flea carboxylesterase. A therapeutic composition of the present invention can also include an excipient, an adjuvant and/or a carrier. Preferred esterase nucleic acid molecule compounds of the present invention include naked nucleic acid vaccines, recombinant virus vaccines and recombinant cell vaccines. Also included in the present invention is a method to protect an animal from hematophagous ectoparasite infestation comprising the step of administering to the animal a therapeutic composition of the present invention.